net/socket/tcp_socket.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/socket/tcp_socket.h"
   6
   7 #include "base/file_util.h"
   8 #include "base/files/file_path.h"
   9 #include "base/location.h"
  10 #include "base/memory/ref_counted.h"
  11 #include "base/threading/worker_pool.h"
  12
  13 namespace net {
  14
  15 namespace {
  16
  17 bool g_tcp_fastopen_enabled = false;
  18
  19 #if defined(OS_LINUX) || defined(OS_ANDROID)
  20
  21 typedef base::RefCountedData<bool> SharedBoolean;
  22
  23 // Checks to see if the system supports TCP FastOpen. Notably, it requires
  24 // kernel support. Additionally, this checks system configuration to ensure that
  25 // it's enabled.
  26 void SystemSupportsTCPFastOpen(scoped_refptr<SharedBoolean> supported) {
  27   supported->data = false;
  28   static const base::FilePath::CharType kTCPFastOpenProcFilePath[] =
  29       "/proc/sys/net/ipv4/tcp_fastopen";
  30   std::string system_enabled_tcp_fastopen;
  31   if (!base::ReadFileToString(base::FilePath(kTCPFastOpenProcFilePath),
  32                               &system_enabled_tcp_fastopen)) {
  33     return;
  34   }
  35
  36   // As per http://lxr.linux.no/linux+v3.7.7/include/net/tcp.h#L225
  37   // TFO_CLIENT_ENABLE is the LSB
  38   if (system_enabled_tcp_fastopen.empty() ||
  39       (system_enabled_tcp_fastopen[0] & 0x1) == 0) {
  40     return;
  41   }
  42
  43   supported->data = true;
  44 }
  45
  46 void EnableCallback(scoped_refptr<SharedBoolean> supported) {
  47   g_tcp_fastopen_enabled = supported->data;
  48 }
  49
  50 // This is asynchronous because it needs to do file IO, and it isn't allowed to
  51 // do that on the IO thread.
  52 void EnableFastOpenIfSupported() {
  53   scoped_refptr<SharedBoolean> supported = new SharedBoolean;
  54   base::WorkerPool::PostTaskAndReply(
  55       FROM_HERE,
  56       base::Bind(SystemSupportsTCPFastOpen, supported),
  57       base::Bind(EnableCallback, supported),
  58       false);
  59 }
  60
  61 #else
  62
  63 void EnableFastOpenIfSupported() {
  64   g_tcp_fastopen_enabled = false;
  65 }
  66
  67 #endif
  68
  69 }  // namespace
  70
  71 void SetTCPFastOpenEnabled(bool value) {
  72   if (value) {
  73     EnableFastOpenIfSupported();
  74   } else {
  75     g_tcp_fastopen_enabled = false;
  76   }
  77 }
  78
  79 bool IsTCPFastOpenEnabled() {
  80   return g_tcp_fastopen_enabled;
  81 }
  82
  83 }  // namespace net